Signal patching allows for placing a device in series with a wire. This allows the patched device to override and patch signals into the wire, thereby controlling other objects or devices connected to the wire.
In order to patch a device into a preexisting wire, one must cut the wire, strip both sides of the cut wire, crimp pins onto each side of the cut wire, and connect the device to the pins. This process is manual, laborious, and time consuming. Further, points where the wire is cut and subsequently reconnected may constitute single points of failure for the whole system. Moreover, often times every wire in a bundle of wires or in a multi-wire cable will have to be cut just to patch into one or two of the wires.